System, method, and computer program product for facilitating communication between devices implementing proprietary features in a DOCSIS-compliant broadband communication system

ABSTRACT

A system, method and computer program product that facilitates communication between devices that implement at least one proprietary feature in a DOCSIS-compliant broadband communication system. A logical channel is established for communication between a first device, such as a cable modem termination system (CMTS), that implements at least one proprietary feature, and other devices that also implement the at least one proprietary feature. Registration information is then received from a second device, such as a cable modem, wherein the registration information indicates that the second device also implements the at least one proprietary feature. In response to receiving the registration information, the second device is assigned to the logical channel.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/440,325, filed on May 19, 2003, which is incorporated herein byreference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is generally directed to broadband communicationsystems. In particular, the present invention relates to broadbandcommunication systems that comply with the Data Over Cable ServiceInterface Specification (DOCSIS), including but not limited toDOCSIS-compliant cable modem communication systems.

2. Background

Conventional cable modem systems utilize DOCSIS-compliant equipment andprotocols to carry out the transfer of data packets between multiplecable modems at the customer premises and a cable modem terminationsystem (CMTS) at the cable headend. The term DOCSIS (Data Over CableSystem Interface Specification) generally refers to a group ofspecifications published by CableLabs that define industry standards forcable headend and cable modem equipment. In part, DOCSIS sets forthrequirements and objectives for various aspects of cable modem systemsincluding operations support systems, management, data interfaces, aswell as network layer, data link layer, and physical layer transport fordata over cable systems, The most current version of the DOCSISspecification is DOCSIS 2.0.

It has been observed, however, that the use of proprietary features orprotocols that are not provided for, or permitted by, the DOCSISspecification may be advantageous within a DOCSIS-compliant cable modemsystem. For example, the modification of certain DOCSIS-defined physical(PHY) layer or Media Access Control (MAC) layer parameters and/or theuse of different PHY or MAC technologies than those supported by DOCSISmay provide a variety of benefits. Such benefits can range fromproviding better system throughput, reducing latency, reducing the costof the cable modem and/or the CMTS, providing a system with bettersignal integrity, providing improved utilization of the spectrum,reducing the area of either the cable modem or the CMTS, or providingbetter noise immunity.

Heretofore, such use of proprietary features that extend beyond DOCSIShas been avoided. This is due, in part, to the fact that the DOCSISspecification does not provide a mechanism for implementing proprietaryfeatures. Moreover, because conventional CMTS and cable modem equipmenthave been designed in accordance with the DOCSIS specification, theimplementation of proprietary features has been avoided to ensureinteroperability between cable modem system components.

Accordingly, what is desired is a system, method and computer programproduct that enables the use of proprietary features that are notprovided for, or permitted by, the DOCSIS specification within aDOCSIS-compliant broadband communication system, such as aDOCSIS-compliant cable modem system. For example, the desired system,method and computer program product should support the modification ofDOCSIS-defined physical (PHY) layer or Media Access Control (MAC) layerparameters and/or the use of different PHY or MAC technologies thanthose supported by DOCSIS. However, the desired system, method andcomputer program product should also be interoperable with DOCSIS in thesense that system components that support the proprietary features canexist on the same network with standard DOCSIS-compliant components thatdo not. Furthermore, the desired system and method should be implementedin a manner that requires minimal modification to the design of existingsystem components, such as the design of existing cable modem and CMTSequipment.

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

The accompanying drawings, which are incorporated herein and form partof the specification, illustrate the present invention and, togetherwith the description, further serve to explain the principles of theinvention and to enable a person skilled in the relevant art(s) to makeand use the invention.

FIG. 1 depicts basic elements of an example DOCSIS-compliant cable modemcommunication system.

FIG. 2 depicts an example DOCSIS-compliant cable modem system thatfacilitates communication between devices implementing proprietaryfeatures in accordance with an embodiment of the present invention.

FIG. 3 illustrates a flowchart of a method for facilitatingcommunication between devices implementing proprietary features in aDOCSIS-compliant cable modem system in accordance with an embodiment ofthe present invention.

FIG. 4 illustrates a flowchart of a method for establishing a logicalchannel that facilitates communication between devices implementingproprietary features in a DOCSIS-compliant cable modem system inaccordance with an embodiment of the present invention.

FIG. 5 illustrates a format of a DOCSIS Upstream Channel Descriptor(UCD) message in accordance with the DOCSIS RFI Specification.

FIG. 6 illustrates a format of a MAC Management Header of a DOCSIS UCDmessage in accordance with the DOCSIS RFI Specification.

FIG. 7 illustrates a flowchart of a method for selectively sending a UCDmessage to devices that implement proprietary features in aDOCSIS-compliant cable modem system in accordance with an embodiment ofthe present invention.

FIG. 8 illustrates a flowchart of a method for selectively sending a UCDmessage to devices that implement proprietary features in aDOCSIS-compliant cable modem system in accordance with an embodiment ofthe present invention.

FIG. 9 illustrates a flowchart of an alternate method for establishing alogical channel that facilitates communication between devicesimplementing proprietary features in a DOCSIS-compliant cable modemsystem in accordance with an embodiment of the present invention.

FIG. 10 illustrates a flowchart of a method for registration of a devicethat implements proprietary features in a DOCSIS-compliant cable modemsystem in accordance with an embodiment of the present invention.

FIG. 11 illustrates an example processor-based system that may implementembodiments of the present invention.

The features and advantages of the present invention will become moreapparent from the detailed description set forth below when taken inconjunction with the drawings, in which like reference charactersidentify corresponding elements throughout. In the drawings, likereference numbers generally indicate identical, functionally similar,and/or structurally similar elements. The drawings in which an elementfirst appears is indicated by the leftmost digit(s) in the correspondingreference number.

DETAIL DESCRIPTION OF THE INVENTION

A. Introduction to DOCSIS 2.0 Logical Channels

Common to all DOCSIS-compliant broadband data communicationarchitectures is the transfer of data between a central location andmany remote subscribers over a shared communications medium. The termsused to describe the central location vary depending on the type ofcommunication architecture: for example, in cable modem systems, thecentral location is typically referred to as the headend, in broadbandterrestrial fixed wireless systems, it is typically referred to as awireless access termination system (WATS), and in two-way satellitecommunication systems, it is typically referred to as the satellitegateway. Terms used to describe subscriber equipment also vary dependingon the type of communication architecture: for example, in cable modemsystems, such equipment is typically referred to as a cable modem (CM),in broadband terrestrial fixed wireless systems, it is typicallyreferred to as a wireless modem (WM), and in two-way satellitecommunication systems, it is typically referred to as a satellite modem(SM).

For the purposes of the description provided herein, terminologypertaining to cable modem systems will be used. However, as will beappreciated by persons skilled in the relevant art(s) based on theteachings provided herein, the present invention is not limited to cablemodem systems, and may be implemented, for example, in anyDOCSIS-compliant broadband communication system.

FIG. 1 depicts basic elements of an example DOCSIS-compliant cable modemsystem 100 in which an embodiment of the present invention may operate.In example system 100, a cable network 106, which typically comprises ahybrid fiber-coaxial (HFC) network, provides a point-to-multipointtopology for supporting the communication of data, such as IP packets,between a cable modem termination system (CMTS) 104 at the cable headendand multiple cable modems (CM) 108 a-108 n at various customer premises.As will be appreciated by persons skilled in the relevant art(s), CMTS104 operates, in part, as an interface between cable network 106 and awide area network (WAN) 102, and each of cable modems 108 a-108 noperates as an interface between cable network 106 and at least onecorresponding customer premises equipment (CPE) 110 a-110 n.

Communication from CMTS 104 to cable modems 108 a-108 n is customarilyreferred to as “downstream” communication, and communication from cablemodems 108 a-108 n to CMTS 104 is customarily referred to as “upstream”communication.

An example CMTS and an example cable modem are fully described in U.S.patent application Ser. No. 09/430,821 to Quigley et al., filed Oct. 29,1999 and entitled “Cable Modem System”, the entirety of which isincorporated by reference as if set forth fully herein.

The DOCSIS Radio Frequency Interface (RFI) Specification defines threedifferent radio frequency (RF) interfaces for cable modem systems: (1)the interface between each cable modem 108 a-108 n and cable network106, (2) the interface between CMTS 104 and cable network 106 in thedownstream direction (toward the customer), and (3) the interfacebetween CMTS 104 and cable network 106 in the upstream direction(traffic from the customer). The most recent version of the DOCSIS RFISpecification is version 2.0, denoted SP-RFIv2.0-I03-021218(hereinafter, “the DOCSIS RFI Specification”), the entirety of which isincorporated by reference herein.

One difference between DOCSIS 2.0 and earlier versions of the standardis that two different burst type formats are supported for upstreamphysical (PHY) layer transmissions between cable modems 108 a-108 n andCMTS 104. In particular, as specified by the DOCSIS RFI Specification,the upstream physical media dependent (PMD) sublayer can use either anFDMA/TDMA burst type format, also referred to as the “TDMA mode,” or anFDMA/TDMA/S-CDMA burst type format, also referred to as the “S-CDMAmode.” In further accordance with the DOCSIS RFI Specification, twotypes of TDMA modes are supported: DOCSIS 1.x TDMA and DOCSIS 2.0 TDMA,which is also referred to as “Advanced TDMA” or “A-TDMA.” Whether acable modem transmits data using DOCSIS 1.x TDMA mode, A-TDMA mode, orS-CDMA mode is configured by the CMTS through the transmission of DOCSISMAC (Media Access Control) Management Messages.

FDMA (frequency division multiple access) indicates that multiple RFchannels are assigned in the upstream band. In accordance with FDMA, acable modem transmits on a single RF channel unless reconfigured tochange channels. TDMA (time division multiple access) indicates thatupstream transmissions have a burst nature. In accordance with TDMA, agiven RF channel is shared by multiple cable modems via the dynamicassignment of time slots. S-CDMA (synchronous code division multipleaccess) indicates that multiple cable modems can transmit simultaneouslyon the same RF channel and during the same TDMA time slot, while beingseparated by different orthogonal codes.

To create a system to allow the above-described TDMA and S-CDMA modes toco-exist, the DOCSIS 2.0 RFI specification has introduced the concept ofa logical channel. Prior to DOCSIS 2.0, each upstream channel wasallocated its own channel frequency. Thus, all channels could be viewedas physical channels. In DOCSIS 2.0, multiple upstream channels,referred to as logical channels, can share the same RF spectrum. Thus, aphysical upstream channel may support multiple logical upstreamchannels. Each logical channel is identified by a unique channel ID. TheCMTS transmits an associated Upstream Channel Descriptor (UCD) and MAPmessage to completely describe the channel.

DOCSIS 2.0 provides four distinct types of logical upstream channels:(1) DOCSIS 1.x upstream channels that support no A-TDMA features; (2)mixed upstream channels that support DOCSIS 1.x and A-TDMA bursts; (3)A-TDMA only upstream channels that cannot support DOCSIS 1.x cablemodems; and (4) S-CDMA upstream channels that support only cable modemsoperating in S-CDMA mode. All valid logical upstream channels must fallinto one of these four categories.

The use of logical channels provides several direct benefits toMulti-System Operators (MSOs) operating DOCSIS 2.0-compliant cable modemsystems. For example, by permitting multiple logical channels thatsupport different burst type formats to share a single physical channel,spectrum utilization may be improved and upstream bandwidth may beconserved. Furthermore, the use of logical channels provides betteroverall system controllability.

B. Facilitating Communication Between Devices Implementing ProprietaryFeatures in Accordance with an Embodiment of the Present Invention

FIG. 2 depicts an example cable modem system 200 that implements amethod for facilitating communication between devices implementingproprietary features in a DOCSIS-compliant cable modem system inaccordance with an embodiment of the present invention. As shown in FIG.2, cable modem system 200 includes a CMTS 202 that is communicativelycoupled via a cable network 204 to a plurality of cable modems 206 a-206n. For the purposes of this example, it is assumed that CMTS 202 andcable modems 206 a-206 n are each configured to support proprietaryfeatures that are not provided for, or permitted by, DOCSIS.

As shown in FIG. 2, CMTS 202 comprises a Media Access Control (MAC)sublayer 208, which in turn comprises an upstream channel manager 210and a registration module 212. Upstream channel manager 210 isconfigured to perform administrative functions related to the managementof upstream communication from cable modems 206 a-206 n to CMTS 202,including but not limited to establishing logical upstream channels. Inthe embodiment depicted in FIG. 2, upstream channel manager 210 isimplemented as part of CMTS MAC 208; however, the invention is not solimited. For example, upstream channel manager 210 can also beimplemented, in whole or in part, as part of an entity external to CMTS202 and communicatively coupled thereto, such as a network managementsystem external to CMTS 202 and communicatively coupled thereto.

Registration module 212 is configured to perform the CMTS portion of acable modem initial ranging and registration protocol described in theDOCSIS RFI Specification, as well as the CMTS portion of a proprietarycable modem registration protocol which will be described in more detailherein.

As will be understood by persons skilled in the relevant art(s) from theteachings provided herein, CMTS MAC 208, and each of upstream channelmanager 210 and registration module 212 may be readily implemented inhardware, software, or a combination of hardware and software. Forexample, based on the teachings provided herein, a person skilled in therelevant art could implement the functions of CMTS MAC 208, and thefunctions of each of upstream channel manager 210 and registrationmodule 212, via a combination of one or more application-specificintegrated circuits and a processor core for implementing softwarecommands stored in one or more attached memories. However, this exampleis not limiting, and other implementations are within the scope andspirit of the present invention.

As also depicted in FIG. 2, each cable modem 206 a-206 n comprises arespective MAC sublayer 214 a-214 n, each of which in tarn comprises arespective upstream processor 216 a-216 n and a respective registrationmodule 218 a-218 na. Each upstream processor 216 a-216 n is configuredto perform functions related to the transmission of data over a logicalupstream channel from the cable modem to CMTS 202. Each registrationmodule 216 a-216 n is configured to perform the cable modem portion of acable modem initial ranging and registration protocols described in theDOCSIS RFI Specification, as well as the cable modem portion of aproprietary cable modem registration protocol which will be described inmore detail herein.

As will be understood by persons skilled in the relevant art(s) from theteachings provided herein, each cable modem MAC 214 a-214 n, and eachrespective upstream processor 216 a-216 n and respective registrationmodule 218 a-218 n, may be readily implemented in hardware, software, ora combination of hardware and software. For example, based on theteachings provided herein, a person skilled in the relevant art couldimplement the functions of each cable modem MAC 214 a-214 n, and eachrespective upstream processor 216 a-216 n and respective registrationmodule 218 a-218 n, via a combination of one or moreapplication-specific integrated circuits and a processor core forimplementing software commands stored in one or more attached memories.However, this example is not limiting, and other implementations arewithin the scope and spirit of the present invention.

FIG. 3 illustrates a flowchart 300 of a method for facilitatingcommunication between devices implementing proprietary features in aDOCSIS-compliant cable modem system in accordance with an embodiment ofthe present invention. The invention, however, is not limited to thedescription provided by the flowchart 300. Rather, it will be apparentto persons skilled in the relevant art(s) from the teachings providedherein that other functional flows are within the scope and spirit ofthe present invention.

Flowchart 300 will be described with continued reference to examplecable modem system 200 described above in reference to FIG. 2. Theinvention, however, is not limited to that embodiment.

The method of flowchart 300 begins at step 302, in which a logicalupstream channel is established to support future communication betweenCMTS 202 and cable modems that implement one or more proprietaryfeatures, such as one or more of cable modems 206 a-206 n. Variousmethods for establishing the logical channel will be described in moredetail herein. At step 304, CMTS 202 receives registration informationfrom a cable modem, such as one of cable modems 206 a-206 n, thatindicates that the cable modem implements at least one of the one ormore proprietary features. The protocol by which this registration iscarried out will also be described in more detail herein. Finally, atstep 306, CMTS 202 assigns the cable modem to the logical channel basedon the receipt of the registration information, at which point the cablemodem may transmit data to CMTS 202 over the logical channel.

C. Establishing a Logical Channel in Accordance with an Embodiment ofthe Present Invention

In accordance with an embodiment of the present invention, a CMTSestablishes a DOCSIS 2.0 logical upstream channel to facilitatecommunication between the CMTS and cable modems that support one or moreproprietary features. The mechanism provided by the DOCSIS RFISpecification for establishing a logical upstream channel is a MACManagement Message, termed an Upstream Channel Descriptor (UCD), whichis broadcast by the CMTS to all cable modems on the network.

However, in accordance with an embodiment of the present invention, theUCD message generated by the CMTS includes parameters not provided foror permitted by DOCSIS that are necessary in order to adequately definethe proprietary logical upstream channel. Receipt of such modified UCDmessages by cable modems that are not configured to process theseparameters may cause these cable modems to malfunction. Thisinteroperability issue is addressed by methods that will now bedescribed.

FIG. 4 illustrates a flowchart 400 of a method for establishing alogical channel that facilitates communication between devicesimplementing proprietary features in a DOCSIS-compliant cable modemsystem in accordance with an embodiment of the present invention. Theinvention, however, is not limited to the description provided by theflowchart 400. Rather, it will be apparent to persons skilled in therelevant art(s) from the teachings provided herein that other functionalflows are within the scope and spirit of the present invention.

The flowchart 400 will be described with continued reference to examplecable modem system 200 described above in reference to FIG. 2. Theinvention, however, is not limited to that embodiment.

The method of flowchart 400 begins at step 402 in which upstream channelmanager 210 determines whether or not a logical channel forcommunication between devices implementing proprietary features shouldbe created, Upstream channel manager 210 may make this determinationbased on a variety of factors including, but not limited to, a defaultnetwork configuration, commands from a system administrator, orregistration by one or more cable modems that support extendedprotocols.

If the upstream channel manager 210 determines that a logical channelshould be created for communication between devices that implementproprietary features, then upstream channel manager 210 generates a UCDmessage defining the logical channel as shown at step 404.

FIG. 5 is provided to illustrate a format 500 of a DOCSIS UCD message inaccordance with the DOCSIS RFI Specification. As shown in FIG. 5, theDOCSIS UCD message includes a plurality of fields, including a MACManagement Message Header 502, an Upstream Channel Identifier (ID) 504that uniquely identifies the logical channel, a Configuration ChangeCount 506, a Minislot Size 508, a Downstream Channel ID 510, TLV-encodedInformation for the Overall Channel 512, TLV-encoded Burst Description514, and TLV-encoded Information for the Subsequent Burst Descriptors516. A description of each of these fields is provided in the DOCSIS RFISpecification (Ver. SP-RFIv2.0-103-021218), which is incorporated byreference in its entirety as if set forth fully herein.

In accordance with an embodiment of the present invention, certainfields within the UCD message generated at step 404 are modified toinclude values that are not provided for or permitted by DOCSIS, but arenecessary to define the logical channel used for communication betweendevices implementing proprietary features. Such modified fields may beincluded, for example, as part of the TLV-encoded Information for theOverall Channel 512, the TLV-encoded Burst Description 514, and/or theTLV-encoded Information for the Subsequent Burst Descriptors 516.

FIG. 6 is provided to illustrate a format 600 of the MAC ManagementMessage Header 502 of UCD message 500 in accordance with the DOCSIS RFISpecification. As shown in FIG. 6, the MAC Management Header 502includes a plurality of fields, including a Destination Address (DA)602, a Source Address (SA) 604, a Message Length (msgLEN) 606, aDestination Service Access Port (DSAP) 608, a Source Service Access Port(SSAP) 610, a Control field 612, a Version field 614, a Type field 616,and a Reserved (RSVD) field 618. A description of each of these fieldsis also provided in the DOCSIS RFI Specification, which is incorporatedby reference in its entirety as if set forth fully herein.

In accordance with an embodiment of the present invention, upstreamchannel manager 210 generates a UCD message at step 404 that has acombination of Version field 614 and Type field 616 that is permitted bythe DOCSIS RFI Specification. The DOCSIS RFI Specification provides thatfor DOCSIS 2.0 only upstream channels, the CMTS must use a value of 3for Version field 614 and a value of 29 for Type field 616. For allother logical upstream channels, the CMTS must use a value of 1 forVersion field 614 and a value of 2 for Type field 616.

At step 406, CMTS 402 transmits the UCD message generated during step404 downstream for receipt by only those cable modems that implement theproprietary features. This step is necessary because the UCD message mayinclude fields that have been modified to include values that are notprovided for, or permitted by, the DOCSIS 2.0 RFI Specification, but arenecessary to adequately define the logical channel that supportscommunication between devices implementing proprietary features asdiscussed above. Therefore, it is essential to ensure that such modifiedUCD messages are not processed by cable modems that do not implement theproprietary features, since such processing may cause those cable modemsto malfunction.

At step 408, each of the cable modems 406 a-406 n receives the UCDmessage. Upstream processors 416 a-416 n within respective cable modems406 a-406 n then process the UCD message to obtain information necessaryfor transmitting data over the logical upstream channel defined by theUCD message.

FIG. 7 illustrates a flowchart 700 of one method for implementing step406 of flowchart 400. As discussed above, step 406 entails transmittinga UCD message downstream for receipt by only those cable modems thatimplement proprietary features. The invention, however, is not limitedto the description provided by the flowchart 700. Rather, it will beapparent to persons skilled in the relevant art(s) from the teachingsprovided herein that other functional flows are within the scope andspirit of the present invention.

The method of flowchart 700 begins at step 702, in which upstreamchannel manager 210 accesses a database of unique identifiers (IDs) ofcable modems that implement proprietary features. In an embodiment, CMTS402 determines whether a cable modem implements proprietary featuresduring a cable modem registration protocol, which is described in moredetail below. Cable moderns so identified during registration are addedto the database. In an embodiment, the cable modem ID comprises a MACaddress of the cable modem. The database of cable modem IDs ispreferably maintained in a memory internal to CMTS MAC 208, although theinvention is not so limited.

At step 704, upstream channel manager 210 generates a separate unicastUCD message for each cable modem having an ID in the database. Eachunicast UCD message is then transmitted downstream for receipt by acorresponding cable modem. By addressing the UCD message to only thosecable modems that implement the proprietary features, this methodensures that cable modems that do not support those features will notprocess a UCD message that includes parameters not provided for orpermitted by DOCSIS.

FIG. 8 illustrates a flowchart 800 of an alternate method forimplementing step 406 of flowchart 400. As shown in FIG. 8, the methodbegins at step 802, in which upstream channel manager 210 accesses aunique identifier of cable modems that implement proprietary features.In an embodiment, the unique identifier comprises a multicast addressthat identifies one or more cable modems that implement proprietaryfeatures. In an embodiment, CMTS 402 assigns the multicast address tocable modems that implement proprietary features during a cable modemregistration protocol, which will be described in more detail below.

At step 804, upstream channel manager 210 generates a multicast UCDmessage addressed to each cable modem encompassed by the identifier. Themulticast UCD message is then transmitted downstream to be received byonly those cable modems. By addressing the UCD message to only thosecable modems that implement the proprietary features, this methodensures that cable modems that do not support those features will notprocess a UCD message that includes parameters not provided for orpermitted by DOCSIS.

FIG. 9 illustrates a flowchart 900 of an alternate method forestablishing a logical channel that facilitates communication betweendevices implementing proprietary features in a DOCSIS-compliant cablemodem system in accordance with an embodiment of the present invention.The invention, however, is not limited to the description provided bythe flowchart 900. Rather, it will be apparent to persons skilled in therelevant art(s) from the teachings provided herein that other functionalflows are within the scope and spirit of the present invention.

The flowchart 900 will also be described with continued reference toexample cable modem system 200 described above in reference to FIG. 2.The invention, however, is not limited to that embodiment.

The method of flowchart 900 begins at step 902 in which upstream channelmanager 210 determines whether or not a logical channel forcommunication between devices implementing proprietary features shouldbe created. If the upstream channel manager 210 determines that such alogical channel should be created, then upstream channel manager 210generates a UCD message defining the logical channel as shown at step904. As discussed above in reference to step 404 of flowchart 400,certain fields within the UCD message are modified to include valuesthat are not provided for or permitted by DOCSIS, but are necessary todefine the logical channel used for communication between devicesimplementing proprietary features.

Unlike the UCD message generated at step 404 of flowchart 400, however,the UCD message generated at step 904 has a combination of Version field714 and Type field 716 that is not permitted by the DOCSIS RFISpecification, but will nevertheless be recognized and accepted by cablemodems that implement proprietary features. Thus, the method offlowchart 900 assumes that upstream processors 216 a-216 n within cablemodems 206 a-206 n are configured to accept UCD messages having aVersion and Type that are different than those permitted by the DOCSISRFI Specification.

In particular, the DOCSIS RFI Specification provides that for DOCSIS 2.0only upstream channels, the CMTS must use a value of 3 for Version field714 and a value of 29 for Type field 716. For all other logical upstreamchannels, the CMTS must use a value of 1 for Version field 714 and avalue of 2 for Type field 716. Thus, in accordance with the method offlowchart 900, the UCD message has a combination of Version field 714and Type field 716 that is not [3, 29] or [1, 2], but is some other setof values that will be recognized only by cable modems that implementproprietary features.

At step 906, CMTS 202 broadcasts the UCD message generated during step904 downstream to all cable modems on the network.

Although all cable modems on the network will receive the UCD message,only those cable modems that implement proprietary features and areconfigured to recognize and accept UCD messages having thenon-conforming Version and Type fields will process the UCD message, asshown at step 908. All other cable modems will discard the UCD messagesfor having an improper Version and Type field combination, therebyensuring that cable modems that do not support proprietary features willnot process a UCD message that includes parameters not provided for orpermitted by DOCSIS.

D. Cable Modem Registration in Accordance with an Embodiment of thePresent Invention

In accordance with an embodiment of the present invention, it isessential that a CMTS that implements proprietary features be aware ofeach cable modem on the DOCSIS-compliant network that also implementsthose features. As will be described in more detail herein, this may beachieved by implementing a proprietary cable modem registration protocolthat is an extension of the standard DOCSIS cable modem registrationprotocol. The protocol enables a CMTS to assign cable modems thatimplement proprietary features to a logical channel dedicated tocommunication with devices that implement those features.

FIG. 10 illustrates a flowchart 1000 of a method for registration of adevice that implements proprietary features in a DOCSIS-compliant cablemodem system in accordance with an embodiment of the present invention.The invention, however, is not limited to the description provided bythe flowchart 1000. Rather, it will be apparent to persons skilled inthe relevant art(s) from the teachings provided herein that otherfunctional flows are within the scope and spirit of the presentinvention.

The flowchart 1000 will be described with continued reference to examplecable modem system 200 described above in reference to FIG. 2. Inparticular, the flowchart 1000 will be described with reference to anexchange of information between CMTS 202 and cable modem 206 a. Theinvention, however, is not limited to this embodiment.

The method of flowchart 1000 begins at step 1002, in which cable modem206 a and CMTS 202 perform initial ranging and registration inaccordance with the standard protocols set forth in the DOCSIS RFISpecification, which are well known in the art. In an embodiment,registration module 212 within CMTS MAC 208 generates messages for theCMTS portion of the protocol, while registration module 218 a withincable modem MAC 214 a generates messages for the cable modem portion ofthe protocol.

As shown at step 1004, after standard DOCSIS initial ranging andregistration has completed, CMTS 202 generates and transmits at leastone unicast UDP message to cable modem 206 a to discover if cable modem206 a supports any proprietary features and to indicate its own supportof proprietary features. In an embodiment, registration module 212within CMTS MAC 208 generates the unicast UDP message using the MACaddress of cable modem 206 a as the destination address.

At step 1006, cable modem 206 a receives the unicast UDP message fromCMTS 202 and, in response, sends a UDP message to CMTS 202 identifyingthe proprietary features that are supported by the cable modem 206 a. Inan embodiment, registration module 218 a within cable modem MAC 214 agenerates this UDP message.

At step 1008, CMTS 202 receives the UDP message transmitted by cablemodem 206 a in step 1006 and, in response, transmits a second unicastUDP message to cable modem 206 a identifying the proprietary featuresthat will be supported during communication with CMTS 202. As will beappreciated by persons skilled in the relevant art(s), the proprietaryfeatures that can be implemented for communication between CMTS 202 andcable modem 206 a will be one or more of those features that are foundin the intersection of the CMTS proprietary feature set and the cablemodem proprietary feature set. In an embodiment, registration module 212within CMTS MAC 208 generates the second unicast UDP message.

At step 1010, CMTS 202 sends a third unicast message to cable modem 206a identifying the appropriate logical channel for upstream transmission,wherein the logical channel supports one or more proprietary featuresimplemented by both CMTS 202 and cable modem 206 a. In an alternateembodiment, the unicast UDP messages sent by CMTS 202 in steps 1008 and1010 are combined into a single unicast UDP message.

The above-described cable modem registration method ensures that cablemodems implementing proprietary features will only transmit in logicalupstream channels dedicated to devices that implement those features.Moreover, once a cable modem has been assigned to a logical upstreamchannel, the CMTS will no longer have to determine whether or not thecable modem supports proprietary features or which features aresupported, since its feature set can be deduced based on transmissionover a particular logical upstream channel.

E. Processor-Based Implementations

As discussed elsewhere herein, various features of the present inventionmay be implemented in software and executed by a processor. FIG. 11depicts an example processor-based system 1100 that may execute softwarefor implementing the features of the present invention, including, butnot limited to, any of the features of CMTS 202 or cable modems 206a-206 n described above in reference to FIG. 2, and any of the methodsteps of flowcharts 300, 400, 700, 800, 900, and 1000 described above inreference to FIGS. 3, 4, 7, 8, 9 and 10, respectively.

As shown in FIG. 11, example system 1100 includes a processor 1102 forexecuting software routines in accordance with embodiments of thepresent invention. Although a single processor is shown for the sake ofclarity, system 1100 may also comprise a multi-processor system.Processor 1102 is connected to a communications infrastructure 1104 forcommunication with other components of system 1100. Communicationsinfrastructure 1104 may comprise, for example, a communications bus,cross-bar, or network.

System 1100 further includes a main memory 1106, such as a random accessmemory (RAM), and a secondary memory 1108. Secondary memory 1108 mayinclude, for example, a hard disk drive 1110 and/or a removable storagedrive 1112, which may comprise a floppy disk drive, a magnetic tapedrive, an optical disk drive, flash memory, or the like. Removablestorage drive 1112 reads from and/or writes to a removable storage unit1114 in a well known manner. Removable storage unit 1114 may comprise afloppy disk, magnetic tape, optical disk, or the like, which is read byand written to by removable storage drive 1112. As will be appreciatedby persons skilled in the relevant art(s), removable storage unit 1114includes a computer usable storage medium having stored therein computersoftware and/or data.

In alternative embodiments, secondary memory 1108 may include othersimilar means for allowing computer programs or other instructions to beloaded into system 1100. Such means can include, for example, aremovable storage unit 1118 and an interface 1116. Examples of aremovable storage unit 1118 and interface 1116 include a programcartridge and cartridge interface (such as that found in video gameconsole devices), a removable memory chip (such as an EPROM, or PROM)and associated socket, and other removable storage units 1118 andinterfaces 1116 that allow software and data to be transferred fromremovable storage unit 1118 to system 1100.

System 1100 further includes a display interface 1120 that forwardsgraphics, text, and other data from communications infrastructure 1104or from a frame buffer (not shown) for display to a user on a displayunit 1122.

System 1100 also includes a communication interface 1124. Communicationinterface 1124 allows software and data to be transferred between system1100 and external devices via a communication path 1126. Examples ofcommunication interface 1124 include a modem, a network interface (suchas Ethernet card or 802.11b interface), a communication port, and thelike. Software and data transferred via communication interface 1124 arein the form of signals 1128 which can be electronic, electromagnetic,optical or other signals capable of being received by communicationinterface 1124. These signals 1128 are provided to communicationinterface 1124 via communication path 1126.

As used herein, the term “computer program product” may refer, in part,to removable storage unit 1114, removable storage unit 1118, a hard diskinstalled in hard disk drive 1110, or a carrier wave carrying softwareover communication path 1126 (wireless link or cable) to communicationinterface 1124. A computer useable medium can include magnetic media,optical media, or other recordable media, or media that transmits acarrier wave or other signal. These computer program products are meansfor providing software to system 1100.

Computer programs (also called computer control logic) are stored inmain memory 1106 and/or secondary memory 1108. Computer programs canalso be received via communication interface 1124. Such computerprograms, when executed, enable system 1100 to perform the features ofthe present invention as discussed herein. In particular, the computerprograms, when executed, enable processor 1102 to perform the featuresof the present invention. Accordingly, such computer programs representcontrollers of the system 1100.

The features of the present invention can be implemented as controllogic in software, firmware, hardware or any combination thereof. In anembodiment where features of the present invention are implemented usingsoftware, the software may be stored in a computer program product andloaded into system 1100 using removable storage drive 1112, hard diskdrive 1110 or communication interface 1124. Alternatively, the computerprogram product may be downloaded to system 1100 over communication path1126. The software, when executed by processor 1102, causes processor1102 to perform features of the invention as described herein.

In another embodiment, features of the present invention are implementedin firmware and/or hardware using, for example, hardware components suchas application specific integrated circuits (ASICs). Implementation of ahardware state machine so as to perform the functions described hereinwill be apparent to persons skilled in the relevant art(s) from theteachings herein.

F. CONCLUSION

While various embodiments of the present invention have been describedabove, it should be understood that they have been presented by way ofexample only, and not limitation. It will be understood by those skilledin the relevant art(s) that various changes in form and details may bemade therein without departing from the spirit and scope of theinvention as defined in the appended claims. For example, the presentinvention is not limited to cable modem systems and equipment asdescribed herein, but is equally applicable to any DOCSIS-compliantbroadband communications system, including but not limited to broadbandterrestrial fixed wireless systems, two-way satellite communicationsystems, and DSL (Digital Subscriber Line) networks. Accordingly, thebreadth and scope of the present invention should not be limited by anyof the above-described exemplary embodiments, but should be defined onlyin accordance with the following claims and their equivalents.

What is claimed is:
 1. A cable modem (CM) that implements at least oneproprietary feature in a cable modem system, wherein the cable modemcomplies with a Data Over Cable Service Interface Specification (DOCSIS)standard, the at least one proprietary feature not being provided for,or permitted by, the DOCSIS standard, the CM comprising: a registrationmodule configured to receive a message from a cable modem terminationsystem (CMTS) that defines a logical channel for communication with theCM and other cable modems that implement the at least one proprietaryfeature not provided for, or permitted by, the DOCSIS standard; and anupstream processor configured to communicate data upstream to the CMTSover the logical channel, wherein said logical channel is derived from asingle physical channel and shares an RF spectrum of the single physicalchannel with at least one other logical channel.
 2. The CM of claim 1,wherein the registration module is further configured to sendregistration information to the CMTS that indicates that the CMimplements the at least one proprietary feature.
 3. The CM of claim 1,wherein the message is an Upstream Channel Descriptor (UCD) message. 4.The CM of claim 1, wherein the message includes at least one proprietaryparameter.
 5. The CM of claim 1, wherein the message includes a versionfield or a type field that comprises a value not provided for by theDOCSIS standard.
 6. The CM of claim 1, wherein the message is a unicastmessage addressed to the CM.
 7. The CM of claim 1, wherein the messageis a multicast message addressed to a plurality of cable modems.
 8. Amethod for communicating data from a first device to a second device,the first device implementing at least one proprietary feature in abroadband communication system that complies with a Data Over CableService Interface Specification (DOCSIS) standard, the methodcomprising: receiving a message from the second device that defines alogical channel for communication with the first device and otherdevices that implement the at least one proprietary feature that is notprovided for, or permitted by, the DOCSIS standard; and communicatingdata upstream to the second device over the logical channel, whereinsaid logical channel is derived from a single physical channel andshares an RF spectrum of the single physical channel with at least oneother logical channel.
 9. The method of claim 8, further comprising:sending registration information to the second device that indicatesthat the first device implements the at least one proprietary feature.10. The method of claim 8, wherein the message is an Upstream ChannelDescriptor (UCD) message.
 11. The method of claim 8, wherein the messageincludes at least one proprietary parameter.
 12. The method of claim 8,wherein the message includes a version field or a type field thatcomprises a value not provided for by the DOCSIS standard.
 13. Themethod of claim 8, wherein the message is a unicast message addressed toa cable modem.
 14. The method of claim 8, wherein the message is amulticast message addressed to a plurality of cable modems.
 15. Themethod of claim 8, wherein the first device comprises a cable modem andthe second device comprises a cable modem termination system (CMTS). 16.A computer program product comprising a non-transitory computer readablestorage medium having computer program logic recorded thereon forenabling a processor to facilitate communication of data from a firstdevice to a second device, the first device implementing at least oneproprietary feature in a broadband communication system that complieswith a Data Over Cable Service Interface Specification (DOCSIS)standard, said computer program logic comprising: instructions forenabling the processor to receive a message from the second device thatdefines a logical channel for communication with the first device andother devices that implement the at least one proprietary feature thatis not provided for, or permitted by, the DOCSIS standard; andinstructions for enabling the processor to communicate data upstream tothe second device over the logical channel, wherein said logical channelis derived from a single physical channel and shares an RF spectrum ofthe single physical channel with at least one other logical channel. 17.The computer program product of claim 16, further comprising:instructions for enabling the processor to send registration informationto the second device that indicates that the first device implements theat least one proprietary feature.
 18. The computer program product ofclaim 16, wherein the message is an Upstream Channel Descriptor (UCD)message.
 19. The computer program product of claim 16, wherein themessage includes at least one proprietary parameter.
 20. The computerprogram product of claim 16, wherein the first device comprises a cablemodem and the second device comprises a cable modem termination system(CMTS).